While we have passed the climatological peak of the Atlantic Basin tropical season, the unfolding weather pattern will become favorable for more tropical activity in the eastern US during the next couple of weeks. Abnormally strong high pressure ridging will set up in coming days over the northeast US and southeastern Canada and this will allow for any potential tropical systems to “slide underneath” and head right towards the US. As a result, close attention should be paid to the Caribbean Sea, Gulf of Mexico and southwestern Atlantic over the next couple of weeks as the Atlantic Basin tropical season drags on.
Very strong high pressure ridging will set up next week across the northeast US and southeastern part of Canada and this type of weather pattern will have two important ramifications. First, above-normal temperatures are very likely to continue in the Mid-Atlantic region and Northeast US into the middle of the month. Second, any potential tropical system that forms in the southwestern Atlantic will be forced to move in an east-to-west direction – and towards the US. There are two tropical systems currently in the Atlantic Basin that are being closely monitored. One system has tropical storm status (named Leslie) and it is out over the central Atlantic with no likelihood of ever getting close to US land. Another disturbance is located in the southwestern Caribbean Sea and this system should be monitored closely in coming days. It looks like it will drift northward in the near term and can go through some intensification while over the warm waters of the Caribbean.
In terms of temperatures, colder-than-normal air has been bottled up over much of Canada during the past couple of weeks and it looks like it will stay up there through at least next week. Given the powerful ridge that is likely to form next week across the NE US and SE Canada, there will be no way for the cold air to drop to the southeast and into the Mid-Atlantic region. In fact, it may take a tropical system in the eastern US to change the overall weather pattern which could then allow for cold air to penetrate into this area. Meanwhile, as the strong ridge pops next week in the NE US, the western US will experience the formation of a deep upper-level trough and much colder-than-normal temperatures. In fact, snow may become rather widespread in many higher elevation locations in the western US later this week and next week as this dichotomy develops with warm weather in the east and cold weather in the west.
Meteorologist Paul Dorian